BEAT cream cheese in large bowl with electric mixer on medium speed until creamy. Gradually add sweetened condensed milk, beating until well blended. Add chocolate and 1 tsp. of the vanilla; mix well. Add eggs, 1 at a time, mixing on low speed after each addition just until blended. Pour over crust.

BAKE 1 hour or until center is almost set. Run knife or metal spatula around rim of pan to loosen cake; cool before removing rim of pan. Refrigerate 4 hours or overnight.